Patent GB-905925-A (GB)
Title: Recovering metal
IPC: B03C1/005
Filed: 1960-04-25
Abstract: 905,925. Magnetic separation; screening apparatus. RATH, F. E. April 25, 1960, No. 14474/60. Class 117. Apparatus for recovering metal pieces and magnetic oxides of selected size range of 3-inch to -12-inch mesh size from a burden comprising a mixture of materials such as are found in steel plant debris comprises a grid 10 having 12-inch grid bar spacing on which the burden is initially deposited. The + 12-inch material resting on the grid is impacted by a magnet carrying crane and any + 12-inch material not broken up is sufficiently magnetic to be removed by the magnet crane. The -12-inch falls through the grid and is carried by a conveyer 11 to a 3-inch mesh roller screen 12 where it is size separated into overs of 3-inch to -12-inch mesh size and throughs of -3-inch mesh size. The overs are conveyed to a rotary impactor 14 where all the friable magnetic portion and part or all of the friable non-magnetic portion are broken up to a maximum size which is below 3-inch mesh size and the metal pieces are cleaned. The impacted burden then passes to a screen 16 of 3-inch mesh size from where the overs, containing clean metal of the selected size range and possibly part of the friable non-magnetic material, are fed to a magnetic pulley separator 18. The magnetic portion passes into a shoot 19 and the non-magnetic portion is fed on to the conveyer 11 for recycling. The throughs from the screens 12, 16 are carried by a conveyer 21 to a cross-belt magnetic separator 22 and a magnetic pulley separator 23, the magnetic material being delivered on to a ¢-inch mesh vibrating screen 24 and the non-magnetic being delivered on to a ¥-inch vibrating screen 27. The overs from the latter pass to a hopper 28b and the throughs to a hopper 29b. The throughs from the screen 24 pass via a rotary drier 32 to a screen 34 of 8 mesh size from where the throughs are delivered to a magnetic concentrator 39. The higher magnetic product containing clean metal particles and magnetic oxides passes to a hopper 41 and the lower magnetic part is conveyed to the hopper 29b. The overs from the screen 34 pass to a magnetic concentrator 43 from where the higher magnetic product is conveyed to a hopper 46 and the lower magnetic part, after passing through a crusher 48, is delivered on to the conveyer 21 for recycling. The overs from screen 24 pass through an impactor 52 to a vibrating ¢-inch mesh size screen 54 from which the overs are conveyed to the hopper 46. The throughs are delivered to the conveyer 21 for recycling. The processed material thus comprises the following classifications: from the shoot 19 clean magnetic metal of 3-inch to -12-inch size range; into hopper 46, 8 mesh to -3-inch metallics and oxides suitable for direct, charging into a blast furnace; in hoppers 28b, 29b, sized non- magnetic material; and into hopper 41, -8 mesh metallics and oxides suitable for charging into a furnace after sintering or agglomerating. Additionally, any metal above 12-inch piece size from the grid 10 is reduced to " charging box " size for open hearth use. In a modification, Fig. 2 (not shown), a further impactor and screening stage is provided.